Ice-crystal growth inhibiting substance

Abstract

An objective to be achieved by the present invention is to provide an ice-crystal growth inhibiting substance which has an excellent ice-crystal growth inhibiting activity suitable for practical use and which can be produced easily, efficiently and economically in safe steps usable in food production. Another objective of the present invention is to provide a method for producing the ice-crystal growth inhibiting substance, a polypeptide which is an active part of the ice-crystal growth inhibiting substance, as well as an ice-crystal growth inhibiting substance composition, a food, a biological sample protectant and a cosmetic each containing the ice-crystal growth inhibiting substance or the polypeptide. The ice-crystal growth inhibiting substance according to the present invention is characterized in that the ice-crystal growth inhibiting substance is derived from a plant, and has a molecular weight of 400 kDa or more as measured by gel filtration chromatography.

1 . An ice-crystal growth inhibiting substance, wherein the ice-crystal growth inhibiting substance is derived from a plant, and has a molecular weight of 400 kDa or more as measured by gel filtration chromatography. 
     
     
         2 . The ice-crystal growth inhibiting substance according to  claim 1 , wherein the ice-crystal growth inhibiting substance is composed of two or more subunits. 
     
     
         3 . The ice-crystal growth inhibiting substance according to  claim 2 , wherein a molecular weight of at lease one subunit is 34000±500 Da or 71000±1000 Da as measured by SDS-PAGE. 
     
     
         4 . The ice-crystal growth inhibiting substance according to  claim 1 , wherein the plant belongs to a family selected from the group consisting of family Brassicaceae, family Apiaceae, family Liliaceae and family Asteraceae, or is an allied species thereof or an improved species thereof. 
     
     
         5 . The ice-crystal growth inhibiting substance according to  claim 4 , wherein the plant belonging to family Brassicaceae is selected from the group consisting of Chinese cabbage, Japanese radish, broccoli, bok choy, komatsuna, turnip, shirona, nozawana, hiroshimana, potherb mustard and mustard, or is an allied species thereof or an improved species thereof. 
     
     
         6 . The ice-crystal growth inhibiting substance according to  claim 5 , wherein the plant belonging to family Brassicaceae is mustard (Brassica juncea), an allied species thereof or an improved species thereof. 
     
     
         7 . The ice-crystal growth inhibiting substance according to  claim 1  wherein the ice-crystal growth inhibiting substance adsorbs on an anion-exchange column at pH 8. 
     
     
         8 . The ice-crystal growth inhibiting substance according to  claim 7 , wherein the anion-exchange column is a DEAE column or a Q column. 
     
     
         9 . (canceled) 
     
     
         10 . The ice-crystal growth inhibiting substance according to  claim 1 , wherein the ice-crystal growth inhibiting substance does not adsorb on a cation-exchange column at pH 6. 
     
     
         11 . The ice-crystal growth inhibiting substance according to  claim 10 , wherein the cation-exchange column is a SP column. 
     
     
         12 . The ice-crystal growth inhibiting substance according to  claim 1 , wherein the ice-crystal growth inhibiting substance does not adsorb on a carbohydrate-binding protein at pH 7.4. 
     
     
         13 . The ice-crystal growth inhibiting substance according to  claim 12 , wherein the carbohydrate-binding protein is ConA. 
     
     
         14 . A method for producing the ice-crystal growth inhibiting substance according to  claim 1 , comprising the step of purifying the ice-crystal growth inhibiting substance from the plant using a separation membrane having molecular weight cut off of 5000 or more. 
     
     
         15 . The production method according to  claim 14 , wherein the ice-crystal growth inhibiting substance is purified by ultrafiltration or reverse osmosis. 
     
     
         16 . A polypeptide, wherein the polypeptide is part of the ice-crystal growth inhibiting substance according to  claim 1 , and has ice-crystal growth inhibiting activity. 
     
     
         17 . The polypeptide according to  claim 16 , wherein the molecular weight thereof is 34000±500 Da or 71000±1000 Da as measured by SDS-PAGE. 
     
     
         18 . An ice-crystal growth inhibiting composition, comprising the ice-crystal growth inhibiting substance according to  claim 1  and/or a polypeptide, wherein the polypeptide is part of said ice-crystal growth inhibiting substance and has ice-crystal growth inhibiting activity. 
     
     
         19 . A food, comprising the ice-crystal growth inhibiting substance according to  claim 1  and/or a polypeptide, wherein the polypeptide is part of said ice-crystal growth inhibiting substance and has ice-crystal growth inhibiting activity. 
     
     
         20 . A biological sample protectant, comprising the ice-crystal growth inhibiting substance according to  claim 1  and/or a polypeptide, wherein the polypeptide is part of said ice-crystal growth inhibiting substance and has ice-crystal growth inhibiting activity. 
     
     
         21 . A cosmetic, comprising the ice-crystal growth inhibiting substance according to  claim 1  and/or a polypeptide, wherein the polypeptide is part of said ice-crystal growth inhibiting substance and has ice-crystal growth inhibiting activity.